Taiko

Taiko uses a multi-tier proof system to validate the state. Currently there are three tiers, SGX tier, 1/8 Guardian tier and 6/8 Guardian tier (from lowest to highest). When proposing a block, the sequencer is assigned the designated prover role for that block. The prover is required to deposit a liveness bond (125.0 TAIKO) as a commitment to prove the block, which will be returned once the block is proven. The SGX tier has a proving window of 5h, during which only the designated prover can submit proof for the block. Once elapsed, proving is open to everyone able to submit SGX proofs. After the proof is submitted, anyone within the cooldown window - for SGX tier is 4h - can contest the block by submitting a bond. For the SGX Proof tier, the validity bond is currently set to 150.0 TAIKO, while 984.375 TAIKO is required to contest the proof. For the Minority guardian tier, validity and contest bonds are set to 225.0 TAIKO and 1476.5625 TAIKO, respectively. It is not required to provide a proof for the block to submit a contestation. When someone contests, a higher level tier has to step in to prove the contested block. Decision of the highest tier (currently the 6/8 Guardian) is considered final. If no one challenges the original SGX proof, it finalizes after 4h (the cooldown window).

All the data that is used to construct the system state is published on chain in the form of blobs. This ensures that it will be available for enough time.

The system uses a based (or L1-sequenced) sequencing mechanism. Anyone can sequence Taiko L2 blocks by proposing them directly on the TaikoL1 contract. The proposer of a block is assigned the designated prover role, and will be the only entity allowed to provide a proof for the block during the initial proving window. Currently, proving a block requires the block proposer to run an SGX instance. Proposing a block also requires depositing a liveness bond as a commitment to proving the block. Unless the block proposer proves the block within the proving window, it will forfeit its liveness bond to the TaikoL1 smart contract.

The system is designed to allow users to propose L2 blocks directly on L1. Note that this would require the user to run an SGX instance to prove the block, or forfeit the liveness bond of 125.0 TAIKO. The TaikoAdmin multisig can pause block proposals without delay.

The user initiates the withdrawal by submitting a regular transaction on this chain. When the block containing that transaction is finalized the funds become available for withdrawal on L1. Finally the user submits an L1 transaction to claim the funds. This transaction requires a merkle proof.